In a long-lasting collagen and its manufacturing method, a pig skin is gone through processes of scraping extra tissues, removing fats, imbibition, digesting, centrifugal separation, salting-out, collecting lower-layer precipitate and freeze-drying to form a collagen, and the collagen is mixed with γ-PGA, and then a glutaraldehyde solution is added and mixed uniformly to perform a first crosslinking and form the long-lasting collagen, so as to overcome the shortcomings of a conventional collagen having a short storage time, a requirement of applying the collagen repeatedly, and a high concentration of remained glutaradldehyde which is biologically poisonous to human bodies.